Relegated to a subspecies of obscurus by Cabrera (1961) and Reig (1978), but Massoia and Fornes (1967) considered the two as distinct species. Distribution documented based on vouchered specimens and clear morphological segregation from N. obscurus underscored by Galliari and Pardiñas (2000). The latter authors regarded the fossil conifer Ameghino as the probable senior synonym for this species but elected to retain benefactus Thomas as the valid name for reasons of familiarity; the possibility of their synonymy requires firm demonstration, with formal suppression of or replacement by the senior name if so.